0.035x+0.045x=427.50
0.08x=427.50
x=427.50/0.08
x=5343.75
x+x+1500=5343.75
2x=5343.75-1500
2x=3843.75
x=1921.88 first
1921.88+1500=3421.88 second
They site there sources or give information to prove why there point is correct
M+1.51 is your answer. first you calculate the difference and then you reorder the values.
Because the situation represents a profit, the integer is 9.
Simple...
you have:

To make this into an improper fraction-->>
1.) Multiply whole number by denominator
2.)Add the number you got plus the numerator
3.) Use the original denominator to finish your improper fraction
Example:

4*9=36
36+4=40

Thus, your answer.