It costs Marci 63 cents to mail a postcard and 89 cents to mail a letter. She sent either a postcard or a letter to each of 13 people and spent $10.27. Let x represent the
number or postcards she wrote, write and solve an equation to determine the number of postcards Marci mailed
Let
x ------> the number of postcards she wrote
y -----> the number of lleters she wrote
we have that
x+y=13 --------> y=13-x -----> equation 1
and
0.63x+0.89y=10.27 ------> equation 2
substitute equation 1 in equation 2
0.63x+0.89(13-x)=10.27
solve for x
0.63x+11.57-0.89x=10.27
0.89x-0.63x=11.57-10.27
0.26x=1.3
x=5
therefore