First, realize that angle ABC is the sum of the two other angles. Hence, form an equation in which you subtract the measure of one of the angles from angle ABC to get the measure of the other angle -- the one you are solving for.
Answer:
≈ 3.14
Step-by-step explanation:
π, or pi, is an irrational number. We mathmaticians round it to 3.14.
How to get answer by Mimiwhatsup (In Decimal Form):

Answer in Fraction Form: 
So r+c=42
c=4+r
subsitute c=4+r for r in r+c=42
r+4+r=42
add like terms
2r+4=42
subtract 4 from both sides
2r=38
divide both sides by 2
r=19
rob=19
subsitute r=19 for r in c=4+r
c=19+4
carly=23