Gabrielle is 15 years younger than Mikhail. The sum of their ages is 61. What is Mikhail's age?
so basically
G=M-15
G+M=61, now solve for M
substitute the first equation into the second one
M-15+M=61
2m-15=61
2m=76
m=38
CHECK
38 + 23 = 61 YAY
