C. 5/2, 3 this is the answer
They mowed total of 11/15 (5/15 + 2/5) already, so they still have 4/15.
Answer:

Step-by-step explanation:
This is a subtraction between polynomials, since both functions are polynomials, hence, to solve the problem with need to perform the subtraction, by coefficients.

By performing the subtraction, we have:

Ok so we know that y=1 so we can simply sub in the value of y into the equation :
y = -5x +3
1 = -5x +3
Move the -5x to the LHS ( Left-hand-side ) therefore it changes sign as well move 1 to the RHS ( Right-hand-side ) it also changes sign.
5x = 3 - 1
5x = 2
x = 2/5
x = 0.4
Hope this helps :).