Question: Can you walk me through the solution of: Rong has been saving 20 coins in his piggy bank every month. Neil has been saving 2/5 times more coins in his piggy bank per month than Rong. How many coins are they having ten years after they started their savings?
Answer: 
Neil has been saving 2/5 times more coins in his piggy bank per month than Rong, a total of 2/5*20 = 8 more coins.
The total number of coins that Neil has been saving in his piggy month per month is 20+8 = 28 coins.
If Rong has been saving 20 coins every month for ten years, the total number of months he's been saving for is 12*10 = 120 months.
Saving 20 coins every month for ten years, Rong has 20*120 = 2400 coins in his piggy bank.
If Neil has also been saving for ten years, he has saved 120*28 = 3360 coins in his piggy bank.
The total number of coins they both have in their piggy banks after ten years of saving is 3360+2400 = 5760