(1) is divided into two parts: 70+70.

(2) One share is divided into 35+35.

(3) Divide 35 into15+20 =15+7 = 20+2 (7 and 2 are weights), put 20 into another 70 to get 90, and the rest is 50.

First, only use the balance of the balance scale to divide140g into two equal parts, 70g each.

The second time, use two weights to weigh out 9 grams of salt from a 70-gram portion.

For the third time, take 9 grams of salt as weight and 2 grams of weight, and weigh out 1 1 g.

So 70+9+11= 90g, and the rest is 50g.

definition

Addition: the operation of combining two numbers into one number.

Subtraction: when two addends and one of them are known, the operation of finding the other addend.

Multiplication: the operation of finding the product of two numbers.

(1) Multiplying a number with an integer is a simple operation, and you can find the sum of several identical addends.

(2) Multiply a number by a decimal to find a few tenths, a few percent and a few thousandths of this number.

(3) A number multiplied by a fraction is a fraction of this number.

Division: the operation of finding another factor by knowing the product of two factors and one of them.