Answer:
r = va/(e - v)
Step-by-step explanation:
v = er/(r + a)
vr + va = er
va = er - vr
va = r(e - v)
r = va/(e - v)
Remember PEMDAS - Parenthesis, Exponents, Multiplication, Division, Addition, Subtraction - this is the order of operations. First, you must distribute 5(x+2), that would be 5x+10. Then rewrite: -3x+5x+10. Finally, simplify.
Simplified: 2x+10
This is your answer
Not sure how the other person got 2x+2...
Hope that helps!
Formula: A = ab/2 unless you need a fully answer question?