# math

posted by on .

can anyone help with this?

suppose you bought some 32 cents stamps and some 20 cents stamps. you spent \$3.92 for 16 stamps. how many of each stamp did you buy?

i got the equation--.32x + .20y = \$3.92 but don't know how to solve for x and y

Step 1: Solve for y in equation (1).

.20y = 3.92 - .32x

Step 2: Substitute this value for y in equation (2). This will change equation (2) to an equation with just one variable, x.

.32x + .20(3.92 - .32x)= 3.92

multiply it out

.32x + (.20 x 3.92) - (.20 x .32x) = 3.92

solve for x, then go back and plug x into the equation and solve for y

yes now i understand the process. i just couldn't get past seeing x and y. thanks

i get
.32x + .784 -.064x = 3.92
.256x + .784 = 3.92
.256x = 3.136

x=12.25?????

Hello Norman, in case u have not solved this yet, try this:

x+y = 16

32x + 20y = 392

You will get whole number answers for x and y.

• math - ,

If you do try hack revise your answer works if you do .32x6 is 1.92 and add .20x10 is 200 and add 1.92 and 2.00 you get 3.92