Carson is covering the high school football field with grass seed. Each square meter needs three times as much seed as fertilizer. If Carson uses 60 gallons of seed and fertilizer combined, how many gallons of seed does he use?
Let s be the number of gallons of seed Carson uses and f be the number of gallons of fertilizer. We know that s = 3f and s + f = 60.
Substituting the first equation into the second equation produces 3f + f = 60
Combining like terms, we get 4f = 60
Dividing both sides by 4, we get f = 15
Substituting that value into the equation s = 3f, we get s = 3 * 15 = <<3*15=45>>45
#### 45