15.39 + 3.96-6.61 = how much, simple operation Remember, simple operation

15.39 + 3.96-6.61 = how much, simple operation Remember, simple operation

Should be:
15.39+3.96-6.61
=15.39-6.61+3.96
=8.78+3.96
=12.74
Maybe it's possible!

Simple calculation of 4.4 × 3.1 △ 3.1 37.3 △ 2.5 △ 4 16.6 × 7 △ 0.8394 △ 5 △ 0.6
I want to ask another question: 4.4 × 31 △ 11

Hello: 4.4 × 3.1 ／ 3.1 = 4.4x1 = 4.4 37.3 ／ 2.5 ／ 4 = 37.3 ／ (2.5x4) = 37.3 ／ 10 = 3.73 16.6 × 7 ／ 0.83 = 16.6 ／ (0.83) X7 = 20x7 = 140 94 ／ 5 ／ 0.6 = 94 ／ (5x0.6) = 94 ／ 3 = 94 / 3

(2 / 15 + 1 / 12) × 3 + 3 / 5 4 / 9 × [3 / 4 - (7 / 16-1 / 4)] simple operation

（2/15+1/12)×3+3/5
= 2/5 +1/4 + 3/5
=2/5+ 3/5 +1/4
= 1+ 1/4
= 5/4
4 / 9 × [3 / 4 - (7 / 16-1 / 4)] simple operation
= 4/9 x 【3/4+1/4-7/16】
= 4/9 x (1-7/16)
= 4/9 x (9/16)
= 1/ 4

How can 7.3 * 14.2-4.2 be easily calculated?
Recursive equation calculation

7.3 * 14.2-4.2 how to calculate easily? 7.3 x (10 + 4.2) - 4.2 = 7.3 x 10 + 7.3x4.2 - 1 x 4.2 = 73 + (7.3-1) x 4.2 = 73 + 6.3 x 4.2 = 73 + 26.46 = 99.46 benefactor, I see that you are a unique talent in the Wulin with unique skeleton, elegant style and wisdom