Since a and 5 aren't like terms, you would write the expression as 
3x(4x - 15) < Given
12x^2 - 45x < Distributive law of property
By the way, you are simplifying not solving. You solve equations and simplify expressions.
Answer:
x = 15
y = 5
Step-by-step explanation:
x = 15
y = 5
We can use ratios, in other words, if one part of the photo is changed x times, how many times does the other part change?
We can set up the proportion as :
width 1 : length 1 = width 2 : length 2
20 : 30 = 5 : x
We do inverse multiplication, or multiply the outer with outer and inner with inner (W1 * L2 and L1 * W2)
20*x = 30*5
20x = 150
Divide all by 10
2x = 15
Divide all by 2 to isolate x
x = 15/2
x = 7.5cm
The solution is 5*125/25 = 25
m=25
