I've included two pictures showing steps on how to solve. Hopefully this helps more than words.
It is c because I had this question on the test
Answer:
The first number is 20, the second one is 11
Step-by-step explanation:
Let the first number be x and the second number be y
Since it says "9 is the difference between two numbers", the first equation will be x-y=9
It also says that "their sum is 31". That means the second equation will be x+y=31
here are the two equations:
x-y=9
x+y=31
You can solve this any way you like, but I'll show elimination
add the two equations
x-y=9
x+y=31
2x=40
divide by 2
x=20
Substitute 20 as x in one of the equations
20+y=31
subtract 20 from both sides
y=11
That means the two numbers are 20 and 11
Hope this helps!
1.
a.) The color of <u>Aqueous solution</u> turns <u>light green</u> from <u>blue</u>, due to formation of <u>iron sulphate</u> .
b.) The color of the <u>Aqueous solution</u> turns <u>colorless</u> from <u>blue</u> due to formation of <u>zinc sulphate</u>.
2. <u>Bells</u> used in temples aren't made up of wood because wood isn't <u>sonorous</u> and hence can't produce <u>ringing sound</u>, and hence metals are used in making bells.
3. <u>phosphorous</u> is kept in water because it is <u>highly reactive</u> and reacts vigorously with air if left free in atmosphere .
4.
a.) CuSO4 + Mg =》MgSO4 + Cu
this is a <u>single displacement reaction</u>, where <u>Magnesium</u> being more reactive than <u>Copper</u>, displaces copper from its compound (copper sulphate) to form <u>magnesium sulphate</u>.
b. H2SO4 + Zn =》ZnSO4 + H2
this is a <u>single displacement</u><u> </u><u>reaction</u>,
where <u>Zinc</u> being more reactive than
<u>hydrogen</u>, displaces hydrogen from its
compound (sulphuric acid) to form <u>Zinc</u><u> </u><u>sulphate</u>.
