3) If the cost of a bread is rupees ( b),find the cost of :
a) butter that is rupees 8 more than the cost of a bread.
b) a pen costs rupees 12 less than four times the cost of a bread.
c) 1L of milk that is 3 times the cost of a bread
Answers
Answer:
If the cost of a bread is rupees ( b),find the cost of :
Answer
Cost of milk = Cost of bread ×3 (given)
=Rs.b×3
=Rs.3b
a) butter that is rupees 8 more than the cost of a bread.
Answer
Cost of butter = cost of bread +Rs.8
=Rs.10+Rs.8
=Rs.18
b) a pen costs rupees 12 less than four times the cost of a bread.
answer
Given total cost of 5 pens and 10 pencil = Rs 30
5 pens + 10 pencils = 30
pens + 2 pencils = 1
also given pen cost 3 more than a pencil
i.e, pen = 3 + pencil.
pen - pencil = 3
pens + 2 pencils = 6
_______________
-3 pencils = -3
pencils = 1
pen - 1 = 3
pen = 4
cost of pencils = 1 cost of pen = 4
c) 1L of milk that is 3 times the cost of a bread
Let m = cost of a liter of milk
Let b = cost of a loaf of bread
Bhavik bought 3 liters of milk and 5 loaves of bread
for a total of $11 so:
3m + 5b = 11
Prices didn't change and he bought 4 liters of milk
and 4 loaves of bread for $10 a month later so:
4m + 4b = 10
We have two equations:
3m + 5b = 11 equation 1
4m + 4b = 10 equation 2
To eliminate a variable we want the coefficients to add to zero.
Multiply equation 1 by 4 and equation 2 by -3. This will give us
12m in the first equation and -12m in the 2nd equation so that
we can then add the two and eliminate the m variable, thus
allowing us to solve for b.
12m + 20b = 44 4(equation 1)
-12m - 12b = -30 -3(equation 2)
---------------------------
0m + 8b = 14 sum of the equations
8b = 14
b = 14/8
b = 1.75
A loaf of bread costs $1.75
Substitute that value into one of the original 2 equations
and solve for m
4m + 4b = 10
4m + 4(1.75) = 10
4m + 7 = 10
4m = 3
m = 3/4
m = .75
A liter of milk costs $.75
A loaf of bread costs $1.75
Check answer:
3m + 5b = 11
3(.75) + 5(1.75) = 11
2.25 + 8.75 = 11
11 = 11
4m + 4b = 10
4(.75) + 4(1.75)=10
3 + 7 = 10
10 = 10
like a butter =45 gdgvkcs gu tati