The answer would be 98. I found this by adding the two numbers together, then subtracting 1, and multiplying that number by the smaller number. It works on every problem you listed.
Here are some examples: 2+3=5-1=4x2=8
3+7=10-1=9x3=27
4+5=9-1=8x4=32
Here is the problem you had trouble with: 7+8=15-1=14x7=98
Do you get it now? If not, just comment and I will answer again. Hope I helped.
Here are some examples: 2+3=5-1=4x2=8
3+7=10-1=9x3=27
4+5=9-1=8x4=32
Here is the problem you had trouble with: 7+8=15-1=14x7=98
Do you get it now? If not, just comment and I will answer again. Hope I helped.