1. In a quadrilateral PQRS, the angles P, Q and R are in the ratio 1:4:8 and their sum is 273degrees.
     Find (a) angle S (b) angle R
 (a) 360-273= 87degrees
      angle S= 87degrees
  
 So you found angle S right ! :)
  
 angle R:
 the angles P, Q and R are in the ratio 1:4:8 and their sum is 273degrees.
 you can write in term s of 1:4:8    1x:4x:8x   and their sum is 273degrees:
 \(x+4x+8x=273 \\ 13x=273 \\ x=21\)
  
 our
 R=8x
 R=168
  
 2.A sum of money is divided in the ratio 2:3:7. Given that the largest share is $112, calculate the smallest share
  
 So the largest is 7x which is 112:
 \(7x=112 \\ x=16 \)
  
 and the smallest one is 2x :
 \(x=16 \\ 2x=32\)
  
 3. Express the following ratio in their lowest forms, giving your answer in the form m:n where m and n are integers.
 (a) 42:30
 \(42:30 \text{ (devide both sides by 2 )}\\ \frac{42}{(2)}:\frac{30}{(2)} \\ 21:15 \text{ (devide both sides by 3 )}\\ \frac{21}{(3)}:\frac{15}{(3)}\\ 7:5\)
  
 for that you need to find common devisor and devide it until you will not left with any common devisor (sorry for english :D).The others in the same rule (if you will stuck write it on the calculator here it will show you it on the fraction form for example:\(\frac12 \)  it is 1:2)