just had this in my sons test

7 12 12 7 17 whats next? answer is 2 how do you get to that?

also any advice how i do these type of questions

100 arrow 180
80 arrow 140
60 arrow 100
50 arrow ? answer 80 ?? how is this worked out?

thanks

terms 1, 3 and 5 are 7,12,17 these increase by 5
terms 2 and 4 are 12 and 7, these dcrease by 5, so term 6 is 7-5 = 2

100->180, 80->140, 60->100, 50->?

1st term increases by 80, 3rd term by 40 (i.e. by half of 1st term amount)
2nd term increases by 60, so 4th term increases by half that amount i.e. 30, 50+30 = 80

thank you

I've got another way to do that question:

Multiply the first number in each pair by 2, then subtract 20 to get the second number.

Therefore 50 x 2 = 100, 100 - 20 = 80, so the answer is 80.

Hope this helped.

very good method. Your method is better than mine. Well done !

thanks, god help my son!