Don't know how to solve

x=12

Step-by-step explanation:

Knowing that everything is given adds up to 90º(because the angle is a right angle), we can easily solve for x.

(x+42)+3x=90

Gather like terms.

4x+42=90

Subtract 42 from both sides of the equation.

4x=48

Divide 4 from both sides of the equation.

x=12

Hope this helps :)

2

step-by-step explanation:

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15