Question

to make 77 + 48 easier to solve, lou decides to first add on from 77 to get to the next ten.
add on to get to 80.
77 + \boxed{3} = 80
now, find the sum.
77 + 48
= 77 + (3 + 45)
= (77 + 3) + 45
= \boxed{125}

Explanation:

Step1: Split 48 into 3+45

$48 = 3 + 45$

Step2: Rewrite the sum

$77 + 48 = 77 + (3 + 45)$

Step3: Regroup terms

$=(77 + 3) + 45$

Step4: Calculate 77+3

$77 + 3 = 80$

Step5: Calculate final sum

$80 + 45 = 125$

Answer:

125