How to calculate, Exercise 3 in Volume 1 Textbook of grade 6 of primary school

How to calculate, Exercise 3 in Volume 1 Textbook of grade 6 of primary school

=1/2*(1/15+1/3)
=1/2*2/5
=1/5
Half is usually represented by 1 / 2, not 2 / 1

A simple algorithm of 7 / 8 times 6 / 5 plus 1 / 8 divided by 6 / 5

7 out of 8 times 6 out of 5 plus 1 out of 8 / 6 out of 5
=7 out of 8 times 6 out of 5 plus 1 out of 8 × 5 out of 6
=1/8×（42/5+5/6）
=1/8×277/30
=277/240

A simple algorithm of 1 / 6 multiplied by 3 / 8 divided by 11 / 6

1 / 6 divided by 11 / 6 multiplied by 3 / 8

Simple algorithm of 1.9 * 4.5-0.45

=（19+1）*0.45=20*0.45=9