Question 749042
x = 42 cent stamp
y = 17 cent stamp

x   +   y = 60....1
42x + 17y = 2170..2
 
Multiply (1) by 42
 
42x + 42y = 2520...1
42x + 17y = 2170...2
Subtract (2) from (1)

       25y = 350
         y = 350/25 = 14

Substitute y = 14 into
x + y = 60
x + 14 = 60
    x  = 60 - 14
    x  = 46
Therefore there are:
  46 x 42 cent stamps and
  14 x 17 cent stamps