A glass is 2 5 full. Then 42cm3 of orange juice is poured in. The glass is now 4 7 full. What is the total volume of the glass?

Question

you need to work out the volume of the  glass

Answer 1

4/7-2/5=20/35-14/35=6/35

42 cm³ represents 6/35 of the total volume

how many 6/35's are in 35/35 ?  (the total volume)

(35/35)/(6/35)=(35/35)*(35/6)=35/6=5 5/6

(5 5/6)*(42)=(35/6)*(42)=35*7=245 cm³ is the total volume

or look at it this way...

35/35-6/35=29/35

29/35=6/35+6/35+6/35+6/35+5/35

we need 42+42+42+42+(5/6)*42 cm³ more for the 29/35

168+35=203 cm³

203+42=245 cm³