Answer:
M = 16
H = 25
F = 50
Step-by-step explanation:
Let's use for abbreviation M for Martina's messages, H for Hong's messages and F for Felipe's messages.
Now we need to write the given information as equations.
Martina, Hong, and Felipe sent a total of 91 text messages
(1) M + H + F = 91
Hong sent 9 more messages than Martina.
(2) H = M + 9
Felipe sent 2 times as many messages as Hong
(3) F = 2 * H
Now with this system, we need to replace the letters to leave only M in the first equation.
(4) M + (M + 9) + (2*(M + 9) = 91
(5) 4*M + 27 = 91
(6) M = (91-27) / 4
Then we find the answer:
M = 16
H = 25
F = 50
