Q1) A teddy bear cost as much as 3 toy crowns. During a sale, both toys were each sold for $12 less. For the new sale prices, a teddy bear cost as much as 6 toy clowns. How much did the teddy bear cost before the sale?

Q2)Thomas is 4 times as old as Sandra.Thomas willbe twice as old as Sandra in 8 years time. How old is Thomas now?

Both of these questions can be solved using the Constant Difference approach. For these questions we notice that both people/items change by the same amount. Since the change is equal the their difference in units must be the same before and after. If they are not we make them the same using LCM.

A teddy bear cost as much as 3 toy crowns. During a sale, both toys were each sold for $12 less. For the new sale prices, a teddy bear cost as much as 6 toy clowns. How much did the teddy bear cost before the sale?

Before
TB --> 3units x 5 --> 15units
TC --> 1unit x 5 --> 5units
Difference (2units x 5 --> 10units))

New Price
TB --> 6units x 2 --> 12units
TC --> 1unit x 2 --> 2units
Difference (5units x 2 --> 10units)

There is a change of 3units each
3units --> 12
1unit --> 4

The Teddy Bear cost 15units --> 15x4 --> $60

Thomas is 4 times as old as Sandra.Thomas will be twice as old as Sandra in 8 years time. How old is Thomas now?

Now
T --> 4units
S --> 1unit
Difference 3units

Eight Years Later
T --> 2units x 3 --> 6units
S --> 1unit x 3 --> 3units
Difference (1unit x 3 --> 3units)

Each changed by 2units
2units --> 8
1unit --> 4

Thomas is 4unit now --> 16 years

Kelyn wrote:
Q2)Thomas is 4 times as old as Sandra.Thomas willbe twice as old as Sandra in 8 years time. How old is Thomas now?
Now
T -> 4u
S -> 1u
Diff. -> 4u - 1u -> 3u

8 years time
T -> 2u x 3 -> 6u
S -> 1u x 3 -> 6u
Diff. -> 6u - 3u -> 3u

From now to 8 years time -> 6u - 4u -> 2u -> 8
1u -> 4
Thomas now -> 6u -> 6 x 4 = 24
Ans: 24 years old