Can anyone pls help me? I am very confuse:

Onsponge Math: P5 percentage:Unit 9.1 : Q1

I do not understand how to explain it to my child:

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Ramesh is 40% heavier than Lionel. If Remesh weighs 49kg, find the weight of Lionel.

The answer given is:

R - 140% (7 units)
L - 100% (5 units)

7 units - 49kg
1 unit - 7kg

Lionel - 5kg - 5 x 7kg = 35kg

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Question: Where do these (7 units) and (5 units) derived from?

Thanks.

Hi there. There are a number ways to represent this. Let me add a few steps / comments ....

Ramesh is 40% heavier than Lionel. If Remesh weighs 49kg, find the weight of Lionel.

Ratio
R : L
140 : 100
7 : 5 (Divide by 20)
49 : 35 (Multiply by 7)

In this case, it is a little difficult to go from 140 to 49 as they do not have a common factor. So instead we make two steps, first to 7 and then to 49.

Unitary (This can sometimes cause confusion if the numbers are not nice as most kids have problem with decimals and/or fractions).

140% --> 49kg
1% --> 49kg/140
100% --> 49kg/140 x 100 = 35kg

Or 140% --> 49kg
20% --> 7kg (Divide both by 7)
100% --> 35kg (Multiply by 5)

Or you can ask your child this:
"If 140units --> 49kg, how much is 100units?"
Doing this will help to walk through the process and most kids are comfortable working with units.
140units --> 49kg
20units --> 7kg
100units --> 35kg
100% --> 35kg