Don't be scared by word problems...just take what you know and plug it into an equation. Twice as long for history as psych, so psych will be X and history will be 2X. You know the total is 12 hours, therefore the equation will be 2X + X = 12. Combine like terms...3X = 12....
Malathion is a pesticide that can affect the nervous system if ingested (often via groundwater)
Set it up like a proportion 200 yds 40 yds ------- = ------ $1.95 x Mutiply top to bottom then divide by your other number 1.95 x 40 = 78 then 78 divided by 200 = $ .39
This looks to me like a fraction. The numerator would be 36+9 and the denominator would be 3x5. The answer would be 45 / 15, which is really just a division problem 45 divided by 15 which would give you an answer of 3.