Question

please as much as you can take you time ans the questions​

Answer 1

Answer:

1 (a) 2(x+y)=42

2x+2y=42

(b) x/y=3/7

7x-3y=0

(c) 4x+10y=4400

(d) x=5+7y

x-7y=5

2.let x be the greater num. than y

according to the question

x+y=60 and

x=8+3y

x-3y=8

on solving we get ,

x=47 and y=13

3. let the speed of the boat in still water be x km/hr and speed of stream be y km/hr

upstream speed=(x-y)km/hr

downstream speed=(x+y)km/hr

according to the question,

case 1

time =distance/speed

so total time taken by the boat to cover 8 km upstream and 32 km downstream is 6hrs

so t1=distance travel in upstream/speed in the upstream

so t1=8/(x-y) and similarly t2=32/(x+y)

and t1 + t2=6hr

so 8/(x-y) + 32/(x-y)=6hrs

case2

similarly, 20/(x-y) + 16/(x+y) =7hrs

and taking 1/(x-y)=p and 1/(x+y)=q

we get,8p+32q=6 implies 4p+16q=3

and 20p+16q=7

on subtracting we get,

p=1/4 and q=1/8

and on putting the values of p and q we get,

x-y=4 and

x+y=8

on adding we get,

x=6km/hr and y=2km/hr

4 let 10 ru. notes be x and 5ru. notes be y

according to the question,

10x+5y=190 implies 2x+y=38 and

5x+10y=185 implies x+2y=37

on multiplying 2 in any equation and then subtracting the two equations we get x=13 and y=12