Need some help with a few questions that have been annoying me

1) Make *s *the subject of the formula below

**v= s (w+x) (thats "S" over "3")**

--

3

2)Simplify Fully

**12s squared t squared**

OVER

16st cubed

3) Solve the simultaneous equasion

3p+q=11.25

p-2q=7.25

4)Show that a solution of the equation

**x Cubed- 10x=35 **

Lies between 4.2 and 4.3

5)Marks jigsaw puzzle contains 3 types of pieces

**>Corner pieces-- 0.008**

>Straight edge pieces--0.164

>Middle pieces-- unknown

Mark picks a piece out at random. The probability's of picking a corner or straight edge piece are shows above

There are 500 pieces in marks jigsaw puzzle

**How many middle pieces are there?**

Thanks in advance to anyone who helps in and if you can will you please show me some formula so i can learn from my mistakes

:>:>