Question

What is the value of x?​

Answer 1

The top smaller sub-triangle and the whole big triangle are similar. This means that the correspondant sides are in proportion. So, we have

`6/ 5 = 54/ 3x+12`

Which implies

`6(3x+12)=5\cdot 54 \iff 3x+12=(5\cdot 54)/(6)=45`

So, we have

`3x+12 = 45 \iff 3x = 33 \iff x=11`