Can anyone help me with this?​

The number of 20sen and 50sen are 40 and 30

Step-by-step explanation:

I. The clues we got are total price and total coins,

If 1RM = 100sen

Given b is 50sen and s is 20sen

So 2,300 = 50b + 20s   => {total price}

70 = b + s  => {total coins}

20* 70 = 20b + 20s  => {simulate}

II. Find b or s value by eliminate one of them

{total price} - {simulate}

2,300 - 1,400 = 50b - 20b + 20s - 20s

900 = 30b

b = 30

III. Find s value by replace b value in {total coins}

70 = 30 + s

40 = s

IV. Prove by replace b and s value in {total price}

2,300 = 50(30) + 20(40)

2,300 = 1500 + 800

2,300 = 2,300 true

That makes 40 coins of 20sen and 30 coins of 50sen.

Hope that help :)