An element with mass of 630 grams decays by 18.8% per minute. how much of the element is remaining after 7 minutes.

146.63 grams.

Step-by-step explanation:

The mass percent that remains after every minute is 100%-18.8 = 81.2% of the initial mass. This means after 1 minute the mass remaining is

After 2 minutes, the mass reaming is

After 3 minutes

so we see the general pattern: the grams remaining after minutes are

Now after 7 minutes the grams remaining are

146.63 grams.

5x + 3y = - 4

step-by-step explanation:

the equation of a line in standard form is

ax + by = c ( a is a positive integer and b, c are integers )

express the line first of all in slope- intercept form

y = mx + c ( m is the slope and c the y-intercept )

to calculate m use the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (7, - 3) and (x₂, y₂ ) = (4, - 8)

m = = -

y = - x + c ← is the partial equation

to find c substitute either of the 2 points into the partial equation

using (4, - 8 ), then

- 8 = - + c ⇒ c = -

y = - x - ← in slope-intercept form

multiply all terms by 3 to eliminate the fractions

3y = - 5x - 4 ( add 5x to both sides )

5x + 3y = - 4 ← in standard form