Answer:
42 min
Step-by-step explanation:
Joanna takes 2 mins to send a text.
2 mins = 2 x 60 sec = 120 sec
Anna takes 40 seconds to send a text
120 ÷ 40 = 3
Anna can text 3 messages in 120 sec
Together, in 120 sec ,
both of them can send out 1 + 3 = 4 texts
Number of 120 seconds needed to send 84 texts
= 84 ÷ 4
= 21
Number of seconds needed
= 21 x 120
= 2520
25020 sec = 2620 ÷ 60 min = 42 min
