# counting problem

• Mar 21st 2010, 09:41 AM
mjoshua
counting problem
Johnny has 76 solid-colored disks that are either red, green, or blue. He lines them up on the floor and finds that there are 4 more red disks that green and 6 more green disks than blue. How many red disks does he have?

Not sure how they're getting 30?
• Mar 21st 2010, 09:53 AM
harish21
Quote:

Originally Posted by mjoshua
Johnny has 76 solid-colored disks that are either red, green, or blue. He lines them up on the floor and finds that there are 4 more red disks that green and 6 more green disks than blue. How many red disks does he have?

Not sure how they're getting 30?

let r= Red disks
g= green disks
and b = blue disks.

then \$\displaystyle r+g+b=76\$

there are 4 more red disks that green means: \$\displaystyle r = g+4\$

6 more green disks than blue means: \$\displaystyle g = b+6\$

from the above equation,you can also write \$\displaystyle b=g-6\$

so \$\displaystyle r+g+b=76\$

or, \$\displaystyle (g+4)+g+(g-6) = 76\$

that gives you \$\displaystyle g = 26\$

and you know that \$\displaystyle r = g+4=26+4=30\$

you can also find out how many blue disks are there.. add the numbers up and you should get 76