Help me
ans should be well explained

Step-by-step explanation:

¡)

The lowest rank of the class is unknown to us.

Let's say, it's x.

highest marks =2 × lowest rank + 7

=> 87 = 2x + 7 (this is the equation we gotta solve)

=> 87 - 7 = 2x

=> 2x = 80

=> x = 40

And x is the lowest rank of the class, so we got the required answer.

¡¡)

it can be 17 since the denominators are in increasing order and 17 only fits in.

I'm looking for any other pattern that can be present here.

b) well because you get well

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116