2/5 = 8/20 and 3/10 = 6/20 which = add the numerator 14 so 14/20 and will have 6 pints left over so she will need to buy 8 pints
see so,1200 kg of coal=1kg of aluminum
if 1 soda can needs 15g of aliminium so
1200/15=80kg coal will be needed for 1 can of soda.
2 goes into 400, that is

,
However, 2 goes into 400,
200 times.