Answer:
You can use a^2+b^2=c^2;
Step-by-step explanation:
42^2+78^2=(6x-1+10x+5)^2
3.5
Triangles always equal to 180
42 + 78 + 16x + 4 = 180
124 + 16x = 180
56 = 16x
3.5 = x
