Here are the equations:
a-b=21
5a-2b=18
Multiply the first equation by 5
5a-5b=105
5a-2b=18 --subtract--
-3b=87
b=-29
So, b=-29 and a=50
You can also see a similar question here that will help you solve this:
https://brainly.com/question/12425898
Chris's answer is good, but you can check this out, too!
https://answers.yahoo.com/question/index?qid=20180930023119AAgSFv6
3(x+5) will be the expression
This similar question will help you:
https://www.quora.com/A-bag-contains-purple-marbles-and-red-marbles-43-in-total-The-number-of-purple-marbles-is-1-less-than-3-times-the-number-of-red-marbles-How-many-purple-marbles-are-there
Check this:
https://www.coursehero.com/file/p7lapjod/How-many-different-combinations-of-pennies-nickels-dimes-andor-quarters-result/
Let's list these out:
24 44
26 64
27 67
22 62
42 66
46 76
47 77
74 72
So, this gives us a total of 16 ways.
This will help you:
http://mathforum.org/library/drmath/view/56129.html
Check this out:
https://www.symbolab.com/solver/solve-for-equation-calculator/solve%20for%20x%5E%7B2%20-%20%5Clog_%7B4%7D%5Cleft(x%5Cright)%7D%20%3D%20%5Cpi
https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:forms-of-linear-equations/x2f8bb11595b61c86:writing-slope-intercept-equations/v/equation-of-a-line-3
