Flip small triangle, so it's the same position as the bigger one.
19cm will match to y
X to 3.6cm
13.5cm to 5.4
Use 13.5cm to 5.4cm o find the scale factor
13.5/5.4 = 2.5 (scale factor)
From 19cm to y, triangle gets smaller.
So, divide by scale factor.
19/2.5 = 7.6cm
Thus, y = 7.6cm
From 5.4 to x, the triangle gets bigger.
So, multiple by the scale factor.
5.4cm x 2.5 = 13.5
Thus, x is 13.5cm
Hope this helps!