I'll give 5 stars, , and brainliest to whoever can answer it correctly and give an explanation.

brian and jake left their homes, which are 500 miles apart, and drove straight towards each other. it took 4 hours for the two to meet. if jake's speed was 15 mph slower than brian's speed, what was brian's speed?

Brian's speed = 70 mph

Work Shown:

B = brian's speed

J = jake's speed

both speeds are in miles per hour (mph)

We're told that "Jake's speed was 15 mph slower than Brian's speed", so

Jake's speed = (brian's speed) - 15

J = B - 15

We'll use this equation later, so set it aside for now.

Now move onto the distance rate time equation d = r*t. Basically you multiply the rate (or speed) by the time to get the distance traveled.

For Brian, he travels at a speed of B mph and does so for 4 hours. His equation is d = r*t ---> d = B*4 > d = 4B

For Jake, its the same story but we use J instead of B. So we have d = 4J

The two distance expressions are 4B and 4J which add to 4B+4J = 4(B+J)

This is then set equal to 500 to get the equation 4(B+J) = 500

Let's go back to J = B-15 and plug this into the equation we just got above

4(B+J) = 500

4(B+B-15) = 500 J replaced with B-15

4(2B-15) = 500

2B-15 = 500/4 ... divide both sides by 4

2B - 15 = 125

2B = 125+15 ... add 15 to both sides

2B = 140

B = 140/2 ... divide both sides by 2

B = 70

Brian's speed is 70 mph

Extra Info:

If you're curious about Jake's speed, then plug B = 70 into J = B-15 to get

J = B-15

J = 70 - 15

J = 55

So Jake is going 55 mph

idk

Step-by-step explanation:

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.