What is 18 X 19 i cants figure it out

WE can do it in many ways, one is this.

We can write 19 and 18 as 20-8 & 20-1

So we can make it like this:-

(20-2)*(20-1) THIS CAN BE SOLVED BY USIND THE IDENTITY OF (x+a)(x+b)=+(a+b)x+ab

Here x=20

         a=-2

         b=-1

So,

20^2+ (-2+-1)20+(-2*-1)

=  400+(-2-1)20+ (-2*-1)

=  400+(-3)20 +(-2*-1)

=  400+ -60 +  (2)

=  400 - 60 + 2

=  340+2

= 342

So 18*19=342

And if you are of lower grades follow this method.

Multiply 18 with 20, you will get 360

Now subtract 18 from 360.

WHAT I DID HERE IS ESTIMATED 19 AS 20 AND THEN SUBTRACTED A 18 FROM THE RECEIVED PRODUCT TO PREVENT CHANGE IN VALUE

the answer for this question is 38

answer: option a.

step-by-step explanation:

you know that the quadrilateral opqr ( a four sided figure) is inscribed in circle. this means that all its vertices are on the circle.

then, by definition, the opposite angles of the quadrilateral are supplementary, this means that the sum of their measures is 180 degrees.

you can observe in the figure that the angles ∠opq   and the angle ∠orq   are opposite, therefore:

then, can be used to d to calculate the measure of ∠opq