4.) Joe, Sam and Chris are all brothers. Joe is 5 years older than Chris and Sam is three times as old as Chris. The sum of their ages is 20. How old is Sam?

step-by-step explanation:

for exempl this   system of equations   y = x - 3

                                                                y = 2x - 5

look   the line : y = x -3     ( red)

                            the line : y = 2x -5 ( bleus)

the answer is d

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