Answer:
Grace jumps for 9 minutes.
Zoe jumps for 12 minutes.
Step-by-step explanation:
Let the time for which Grace jumps the rope = [tex]x[/tex] minutes
Let the time for which Zoe jumps the rope = [tex]y[/tex] minutes
As per question statement:
[tex]x+y=21 ..... (1)[/tex]
Number of times Grace jumps in one minute = 66
Number of times Zoe jumps in one minute = 56
Number of times Grace jumps in [tex]x[/tex] minutes = 66
Number of times Zoe jumps in [tex]y[/tex] minutes = 56
As per question statement:
[tex]66x+56y=1266 ...... (2)[/tex]
Multiplying equation (1) with 66 and subtracting equation (2) from it:
[tex]10y = 1386 - 1266\\\Rightarrow 10y=120\\\Rightarrow y =\bold{12\ min}[/tex]
By equation (1):
[tex]x=21-12=\bold{9\ min}[/tex]
Therefore, the answer is:
Grace jumps for 9 minutes.
Zoe jumps for 12 minutes.