解方程 f1

1.) 6 times of a number is greater than 4 times of the number by12.Find that number.
let the number is x
Then
6x=4x+12
2x=12
x=6
The number is 6
2.) The total marks scored by a team in a competition is represented by the algebraic expression 100 + 20y, where y stands for the number of questions that are correctly answered .If team A scores 340 maeks , how many questions does the team answer correctly?
Set
100+20y=340
y=(340-100)/20
y=240/20
y=12
The team answers 12 questions correctly.
3.) the total weight of a dog and a cat is 15.4 kg. the dog is six times as heavy as the cat .Find the weight of the cat.
Let the weight of the cat is x kg
Then the weight of the dog is 6x kg
x+6x=15.4
7x=15.4
x=2.2
The weight of the cat is 2.2 kg
4.) Divide $790 between A,B,C so that A may have $150 more than B , and B have $80 more than C . How much does C have?
Let C has $ x
Then B has $ x+80, A has $ x+80+150=x+230
x+230+x+80+x=790
3x+310=790
3x=480
x=160
C has $ 160