Each option: 1 Mark
(i) p+q+3r,when p=1,q=5,r=2
p+q+3r=1+5+3(2)=12
(ii) 2a+4b+5c, when a=5,b=10,c=20
2a+4b+5c=2(5)+4(10)+5(20)
=10+40+100=150
(iii) 3a−2b, when a=8,b=10
3a−2b=3(8)−2(10)
=24−20=4
(iv) 5x+3y−6z, when x=3,y=5,z=4
5x+3y−6z=5(3)+3(5)−6(4)=15+15−24
=30−24=6