What is the number that should replace y?
23−12×(−5)+y:7+[21−4]=107
We begin by solving the multiplication exercise:
12×(−5)=−60
and subsequently the exercises within brackets:
21−4=17
We obtain the following:
23−(−60)+y:7+17=107
Keep in mind that a negative times a negative becomes a positive:
23+60+y:7+17=107
Next we simplify and add:
23+60=83
83+17=100
We obtain the following calculation:
100+y:7=107
We then rearrange the sections:
y:7=107−100
7y=7
Lastly we multiply by 7:
y=7×7=49