90° is the correct answer
Answer: 
<u>Step-by-step explanation:</u>
(4, 1) & (2, -5)
First, find the slope (m) and then the perpendicular (opposite reciprocal) slope:

Next, find the midpoint of (4, 1) and (2, -5):

Lastly, input the perpendicular slope and the midpoint into the Point-Slope formula to find the equation of the line:

The fraction of the total number of marbles is left in the bag after removing and giving part to her friend is 3/8
<h3>Fraction</h3>
let
- Number of marbles in her bag = x
- Number of marbles removed from her bag = 1/2x
Remaining marbles = x - 1/2x
= (2x-x) / 2
= x/2
= 1/2x
Number of marbles given to her friend = 1/4 of 1/2x
= 1/4 × 1/2x
= 1/8x
Number of marbles left in the bag = Remaining marbles - Number of marbles given to her friend
= 1/2x - 1/8x
= (4x-x) / 8
= 3x/8
= 3/8x
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Answer: Side of largest square tile will be 105 feet.
Explanation:
Since we have given that
dimensions of the wall is 42 feet by 10 feet
So,
Length of wall = 42 feet
Breadth of wall = 10 feet
First we calculate the H.C.F. of 42 and 10,
which is 2 only.
The largest square tile side would be 2 feet.
Now, we find the number of tiles used,
Number of tiles =

We get integer value of number of tiles.
Therefore, Side of largest square tile will be 2 feet.
The time it will take to fill the vat if both pipes are left open is = 4.3 hours
<h3>Calculation of time taken to fill vat</h3>
The number of pipes a vat has = 2
The time it takes the inlet pipe to fill the vat = 3hrs
The time it takes the outlet pipe to empty the vat= 10hrs
Therefore, the time it will take to fill the vat if both pipes are left open is;
1/t = 1/3-1/10
1/t = 7/30
Make t the subject of formula,
t = 30/7
t= 4.3 hours
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