when planning his crops, farmer tim knows that his 7 acres can support peas and carrots. he wants to make $7,000 from his crops. he can make $2,000 per acre of peas (the variable p) and $1,000 per acre of carrots (the variable c). which equation below would be a constraint in his system of equations? a. 2,000p 1,000c = 7,000 b. 2,000p − 1,000c = 7,000 c. p c = 7 d. c − p = 7