Question

mary and her brother john collect foreign coins. mary has 3 times the number of coins that john has. together they have 180 foreign coins. find how many coins mary has.

Answer 1

total is 180
m+j=180

m has 3 times j
m=3j

sub 3j for m
3j+j=180
4j=180
divide both sides by 4
j=45
sub
m=3j
m=3(45)
m=135

mary has 135 coins