(-123)×(-4)+125×(-5)-127×(-4)-5×75= It must be right, please

(-123)×(-4)+125×(-5)-127×(-4)-5×75= It must be right, please

(-123)×(-4)+125×(-5)-127×(-4)-5×75=\
=123*4+125*(-5)+127*4-5*25*3
=(123+127)*4+125*(-5)-125*3
=250*4-125*(5+3)
=0

123+234+354-456+567-678+789

123+234+354-456+567-678+789
=(1+2+3-4+5-6+7)*100+(2+3+5-5+6-7+8)*10+(3+4+4-6+7-8+9)
=800+120+13
=933

one hundred and twenty-three
There are several balls in the bag, of which red balls account for 5 / 12. Later, six red balls were put into the bag. At this time, red balls account for 1 / 2 of the total. How many balls are there in the bag now?

Let X be original
(5/12X+6)/(X+6)=1/2
X=36
36 + 6 = 42