Answer:
The student made the first mistake in step 2.
Step-by-step explanation:
The smaller number is 5.
The bigger number is 15.
Let the smaller number be x and the bigger number be x+10.
x+x+10 = 4x
2x+10 = 4x
10 = 4x-2x
2x = 10
x = 10÷2
= 5
x+10 = 5+10
= 15
6^21 = B
x=100
