Answer with explanation:
→59 + 17
59 = 60 -1, 17 = 20 -3
= (60 - 1) + (20 -3)
Opening the smaller brackets
= 60 -1 +20 -3
= 60 +20 -1-3→→Using the associative Property of addition,that is [a + (b +c)]=[(a+b)+c]
= 80 -1 -3
= 80 -4
=76
→→I have made two new tens to solve this problem, one while writing, 59 =60 -1, and another one ,while writing number, 17=20 -3.
≡2nd way
5 9 + 17
= 59 +(16 +1)
=59 + 16 +1 →→Opening the smaller bracket
=59 +1 +16 →→Using the associative Property of addition,that is [a + (b +c)]=[(a+b)+c]
=60 +(10 +6)
=60 +10+6 →→Opening the smaller bracket
=70 +6
=76
Here i have made one ten,only while writing number ,16 =10 + 6.