The answer is a).
When doing estimation you put it to the nearest number. 24--> 25
21-->20.
The common multiple of 25 and 20 is 100 (25*4=100 and 20*5=100) and now you have found the common denominator. So you would do 17*4= 68 and 13*5=65
68+65=133
133 on 100 is obviously greater than 1.
B) 9*4=36 and 10*5=50 36+50=86
86 on 100 is not a greater sum than 1.
C) 12*4=48 and 9*5=45
48+45=93
93 on 100 is not a greater sum than 1.
I'll let you do D) so you can practice :)
Have a nice day/night and I hope I've helped you out!
~Soringthroughthesky
