Solve the simultaneous equations:
4x+7y=1
3x+10y=15

Ok we need a common coefficient of either x or y:
12x+21y=3
12x+40y=60
We can subtract one from the other to get:
19y=57
Now divide by 19 to get:
y=3
Now if we sub this back in we see that:
3x+30=15
3x=-15
x=-5

The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.