I will gladly support you in completing these and learning how to complete them yourself for the tests.
Any time the question is what % OF X is Y or if the question asks what% OF x is y, etc, it's asking for a multiplication. OF means multiplication.
5. What we know. ..
Man mass is 78.2kg
Luggage is 19.3kg
n% of man's mass is luggage
n% ร 78.2kg = 19.3
n/100 ร 78.2 = 19.3
Solve for n I'll complete only this one so you can use it as example
n% ร 78.2 = 19.3
n/100 ร 78.2 = 19.3
n/100 = 19.3 รท 78.2
n = 19.3รท78.2ร100
n = 1930รท78.2
n = 24.68
6. Salt = Sodium + Chlorine
Total Salt = 117g
contains Sodium = 46g
Chlorine = 117g - 46g = 71g
Equation for Sodium:
N% of Total Salt is Sodium
N% ร Total Salt (117) = Sodium (46)
Equation for Chlorine
N% of Total Salt is Chlorine
N% ร Total Salt (117) = Chlorine (71)
Follow steps under #5 to complete these equations, if you need help
7. Original Gum Mass = 8g
Remaining Gum Mass = 3.4
Lost Gum Mass = 4.6
Equations
A. What% of Original Mass is Remaining Mass
N% of Original Mass(8) is Remaining Mass (3.4)
N% ร 8 = 3.4
N% = 3.4/8 = .425
N = .425 ร 100 = 42.5%
B. What% of Original Mass is Lost Mass
N% of Original Mass (8) is Lost Mass (4.6)
N% ร 8 = 4.6
N% = 4.6/8
N% = .575
N = .575 ร 100 = 57.5%
8. Magazine = 128p
Adverts = 23
Photos = 32
Adverts
N% of Magazine = Adverts
N% of Mag (128)= Ads (23)
N% ร 128 = 23
you finish
Photos
N% of Magazine is Photos
N% xMag(128) =Photos(32)
N% ร 128 = 32
you complete
9. Air = 40
Nitrogen = 5
Oxygen = 1.34
Other Gasses = 33.66
Nitrogen
N% of Air is Nitrogen
N% of Air (40) is Nitro (5)
N% ร 40 = 5
Oxygen
N% of Air is Oxygen
N% of Air(40) is Oxy(1.34)
N% ร 40 = 1.34
Other Gasses
N% of Air is OG
N% of Air(40) is OG(33.66)
N% ร 40 = 33.66
10. # People 50
Increased by 10
is 10 people 20% of 50?
Test it. ..
20% of 50 = 10
20% ร 50 = 10
20% = 10/50 = .20
20 = .20 ร 100 = 20
B.50+10=60
Another 10 people enter
Is 10 20% of 60?
20% ร 60 = 10
20% = 10/60 = .166
20=.166ร100=16.6
10 is Not 20% of 60