so, for this one you first figure out how many study French.
2/9 of 270 is 60 (simple method: 1/9 is 270 divided by 9, which is 30. So 2/9 is 1/9 multiplied by 2, which is 60). 60 are doing French.
Then use this in the ratio of French to Spanish (3:7) and you have 3 and 60 on the same side. You have to multiply 3 by 20 to get to 60 (or divide 60 by 20 to get 3). So the number you use to do the same to the other side of the ratio is 20.
7 multiplied by 20 (or 7 multiplied by 10, then multiply that by 2) to get 140. 140 are doing Spanish.
Then take the French and Spanish from the big total and you get 270-140-60=70 70 are doing German.
Of these 70, 42 are boys. 70-42 gives 28 girls. 42/70 is the fraction of boys doing German. This is the same as 6/10 and to get a percentage you multiply the fraction by 10 so that the bottom of it is out of 100 (so that’s 60/100).
