Answer:
h=7
Step-by-step explanation:
First we need to define the formula for surface area
2(wl+hl+hw)=100
Now we can replace length with x
That makes width .5x and height x+3
2(.5x^2+x^2+3x+.5x^2+1.5x)=100
2(2x^2+4.5x)=100
2x^2+4.5x=50
2x^2+4.5x-50=0
Insert into quadratic equation (a=2x^2, b=4.5, c=-50)
x=4 or -6.25
x can't be negative so x is 4
h=x+3=7
h=7
