Question

For triangle abc angle a = 35 angle b = 55 and side c = 70 find side b to the nearest whole number

Answer 1

See the attached picture. You basically just need to use the Law of Sines.

Answer 2

It´s an right triangle because it has an angle with 90º.
A=35º
B=55º
A+B+C=180º
35º+55º+C=180º
C=180º-35º-55º
C=90º

We have in this triangle:
B=55º
b=opposite (whith respect to angle B)
c=hypotenuse (because it´s in front of the right angle)

sin Ф = opposite/ hypotenuse

In this case:
sin 55=b/70
b=70(sin 55º)
b=57.34....≈57

answer: the length of the side b would be 57 u (u=units of lengths)