Question 993627
p = number of 1 peso coins
n = number of 5 peso coins
d = number of 10 peso coins


p + 5n + 10d = 2980
n = 2p
d = n + 50


Write everything in terms of p.


p + 5(2p) + 10(2p + 50) = 2980
p + 10p + 20p + 500 = 2980
31p = 2480
p = 80


Mandy has 80 1-peso coins, 160 5-peso coins, and 210 10-peso coins.