Question 159749
You were on the right track, but got off on a siding...


5c+3d=11
5c-d=5


5c-d=5
d=5c-5


5c+3(5c-5)=11
5c+15c-15=11
Up to this point, you were spot on, but


20c-15+15=11+15
20c=26
c=1.3


Then

d = 5(1.3) - 5
d = 6.5 - 5 = 1.5


Check

5(1.3)+3(1.5)=6.5+4.5=11  Checks.