A bricklayer's apprentice takes 10 hours longer than the bricklayer to make a fireplace. The apprentice worked alone on a fireplace for 5 hours, after which the bricklayer began to help. It took 2 more hours for them to finish the fireplace. How long would it take the apprentice to make the fireplace on his own?

It would take the apprentice 14 hours to make the fireplace on his own.

Step-by-step explanation:

Let x represent the hours it takes the bricklayer to make a fireplace on his own and x + 10 represent the hours it takes the bricklayer's apprentice to make a fireplace on his own.

7/(x + 10) + 2/x = 1

7/(x+10) represents the fraction of the fireplace the bricklayer's apprentice made (total amount of time the bricklayer's apprentice worked on the fireplace/time it takes the bricklayer's apprentice to make a fire place on his own) while 2/x represents the fraction of the fireplace the bricklayer made (total amount of time the bricklayer worked on the fireplace/time it takes the bricklayer to make a fire place on his own). The 1 on the right side of the equation represents the number of fireplaces they made in that time.

Multiply both sides of the equation by x(x + 10) to get rid of the denominators:

x(x + 10)[7/(x + 10) + 2/x] = x(x + 10)1

x(x + 10)[7/(x + 10)] + x(x + 10)(2/x) = x(x + 10)

7x + 2(x + 10) = x² + 10x

7x + 2x + 20 = x² + 10x

Gather all the terms to one side of the equation:

x² + 10x - 7x - 2x - 20 = 0

x² + x - 20 = 0

Factoring the simplified equation:

(x + 5)(x - 4) = 0

Solving for each factor:

When x + 5 = 0,

x = -5

When x - 4 = 0,

x = 4

Since a negative solution wouldn't make sense for this question, it would take the bricklayer 4 hours to complete the fireplace on his own.

Substituting x = 4 into x + 10 to find out how long it would take the apprentice to make the fireplace on his own:

x + 10 = 4 + 10 = 14

Therefore, it would take the apprentice 14 hours to make the fireplace on his own.

x > 1.3

step by step:

8.5−0.9x> 9.8−1.9x

step 1: simplify both sides of the inequality.

−0.9x+8.5> −1.9x+9.8

step 2: add 1.9x to both sides.

−0.9x+8.5+1.9x> −1.9x+9.8+1.9x

1x+8.5> 9.8

step 3: subtract 8.5 from both sides.

1x+8.5−8.5> 9.8−8.5

1x> 1.3

step 4: divide both sides by 1.

1x/1 > 1.3/1