Need help will mark brainliest

Step-by-step explanation:

a. RG=36 since RG=2(RT)

b.

4x+12=10x-15 Since RG and HI are equivalent

12=6x-15 Subtract 4x from both sides

27=6x Add 15 to both sides

4.5=x Divide by 6 on both sides

to double check:

4(4.5)+12=30

10(4.5)-15= 30

so x=4.5

Step-by-step explanation:

I think the function is 1800(1.22)^x, not 1800(1.22)x

Growth rate is 22% per year.