Question

A man went to a post office to buy stamps. He bought x, 50 cent stamps and y, 25 cent stamps for $3.50. If he bought twice as many 50 cent stamps and half as many 25 cent stamps, the cost would be $4.75. Evaluate x and y

Answer 1

total cost for x,y

50x + 25y = 350

total cost for new x,y

50(2x) + 25(y/2) = 475

Putting it together:

50x + 25y = 350
100x + 25/2 y = 475

or, with no ugly fractions

50x + 25y = 350
200x + 25y = 950

Subtract top from bottom

150x = 600
x = 4
y = 6

50(4) + 25(6) = 350
50(8) + 25(3) = 475