To ask for maths help again

[Polkadotpjs]

I can’t decide if we are supposed to make this into algebra or trial and error or put brackets round the middle bit or all or none of this! Help please

If primary, it's probably trial and error.
But, if your child has done algebra, it's a case of forming an equation:
7x - 4 = 3x + 2
Leading to
4x = 6
x = 1.5

Scratch that! Working on it.

7x - 4 = 3 (3x + 2)
7x - 4 = 9x + 6
-10 = 2x
x = -5
This gives the results
-39 and -13

X = -5

Haha, I was just going to type that out @mineofuselessinformation.

The key is knowing that the formula to machine A is the same as 3 of the formula of machine B.

Algebra, definitely.

x is the input. You want 7x - 4 to be the same as 3x + 2, so you just make the equation and solve it.

Use algebra to make two equations with an input of x and output of y;

7x- 4 = 3y
3x +2 = y

Then solve the simultaneous equations;

7x-4=3(3x+2)
7x-4=9x+6
7x-9x=6+4
-2x=10
X=10/-2
X=-5

7x - 4 = 3y
and 3x + 2 =y

So 9x + 6= 3y (multiply the second equation by 3)

9x + 6 =7x -4
9x +10 = 7x
10 =7x -9 x = -2x
-x = 5
x= -5

I think. Put -5 as the inputvto bith and see if it works?

Bother it took me so long to type that on my phone grrrr

Given it says number machines, chances are you aren't doing simultaneous equations.

Yep x=-5

Is it sad that I actually quite enjoyed doing that?

I agree, chomalungma

Most likely the missing digits are:
4, 24
2, 8

I went with trial and error and got input for A=4 and input for B=2

@WhoAmIGoingToBeToday - both machines have the same input

The inputs must be the same

-5

Algebra

See if got a formula written but the wrong one. Must try harder. I got an A when I did GSCE. My poor son is doomed !
Thanks all

Number machines seem to feature at GCSE

here so simultaneous equations seem entirely appropriate as a way of solving the question.