Question

What is the solution of p+15=a and 5a-525=2p

Answer 1

You have a system of equations going on here.  The first one is already set equal to a. So let's take that part of the equation, the p + 15, and sub it in for the a in the other equation: 5(p + 15) - 525 = 2p.  Now what we have is an equation to solve that is only in terms of p, not p and a.  We cannot solve an equation with 2 unknowns.  Making that substitution eliminates the a, the second unknown. Now distribute the 5 into the parenthesis to get 5p + 75 - 525= 2p.  Move the 2p over to the left and move the other terms over to the right and combine all the like terms to get 3p = 450.  Dividing both sides by 3 gives you that p = 150.  Now take that p value and sub it into the p + 15 = a to get 150 + 15 = a and a = 165

Answer 2

P + 15 = a
5a - 525 = 2p
The first equation is already set equal to a, so plug it into the second equation for a.
5(p + 15) - 525 = 2p
Distribute.
5p + 75 - 525 = 2p
Combine like terms.
5p - 450 = 2p
Subtract 5p from both sides.
- 450 = - 3p
Divide both sides by - 3
150 = p
p + 15 = a
150 + 15 = a
165 = a
a = 165, p = 150