1. 18 multiplied by -7/6 is -21
2. 8 multiplied by -4/5 multiplied by -10 is the same as -80 multiplied by -4/5 which is 64
3. 15 multiplied by -2/3x is -10/x
this can all be done without a calculator. I didnt use one and im sure my answers are correct but you could always check with one just in case :)