3.5×6.4+3.5×3.6 = 3.5X(6.4+3.6)= 3.5X 10 = 35

3.7×9.9 = 3.7x 10-3.7x 0. 1 = 37-0.37 = 36.63

100-34.52-65.48= 100-(34.52+65.48)

Method-12.5X5+705X5

Method 2 (12.5+7.5)X5

24X4X2.5 or 2.5X24X4

The above problems are relatively basic, and you need to use algorithms to master simple calculations. I wish you progress in your study.