One number is 7 more 3 times another number. the sum is 75. what is the smaller number

Greetings from Brasil...

According to the statement of the question, we can assemble the following system of equation

X = 7 + 3Y i

X + Y = 75 ii

So, multiplying ii by -1 and adding with i

X = 7 + 3Y

- X - Y = - 75

- Y = 7 + 3Y - 75

4Y = 68

Y = 17

for X we will use ii:

X + Y = 75

X + 17 = 75

X = 58

The smaller number is: 17

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer