Answer:
x=7
Step-by-step explanation:
4x+12=40
-12
4x=28/4
15/10 = 18-x/x is the ratio of the larger to the smaller triangle
Cross multiply:
15x = 10(18 - x)
15x = 180 - 10x
25x = 180
x = 7.2
Plug back in to check
15/10 = 1.5
18-7.2/7.2 = 10.8/7.2 = 1.5 :)
5
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