Answer:

Step-by-step explanation:
In order to get the answer to this question you need to turn the scientific notations into standard form then subtract the two standard forms.

Turn the notations into standard form:




Turn into notation form:

Hope this helps.
Answer:
<h3>285.15</h3>
Step-by-step explanation:
Given the expression;
19/258 = 21/x
We are to find the unknown value x;
Cross multiply;
19 * x = 258 * 21
19x = 5418
Divide both sides by 19;
19x/19 = 5418/19
x = 285.15
Hence the unknown value is 285.15
Abd is a right angled triangle so by pythagoras we know

and to calculate h we need to use the sine rule

i hope this helps
Answer:
Johnny is wrong.

Step-by-step explanation:
Johnny is wrong.
A better definition would be:
is the set of all elements that belong to at least one A or B.
So, the elements that belong to both A and B, like c and d in this exercise, also belong to
.
So:

A-3b=9
a=b-3
b-3-3b=9
-2b-3=9
-2b=12
2b=-12
b=-6
a=-6-3
a=-9
Solution: (-9,-6)
----
Check:
-9=-6-3
-9=-9
TRUE