You labeled the triangle wrong sides 'a' and 'b' are supposed to be the sides that make the right angle. the other side is called the hypotenuse which is the longest side which you should have labeled 'c'
so Pythagorean theorem says
a^2+b^2=c^2
so
(2x+1)^2+(11x+5)^2=(12x+1)^2
distribute
(4x^2+4x+1)+(121x^2+110x+25)=(144x^2+24x+1)
add like terms
125x^2+114x+26=144x^2+24x+1
subtract 125x^2 from both sides
114x+26=19x^2+24x+1
subtract 114x from both sides
26=19x^2-90x+1
subtract 26 from both sides
0=19x^2-90-25
factor
(x-5)(19x+5)=0
therefor x-5=0 and/or 19x+5=0
so
x-5=0 add 5 to both sides
x=5
19x+5=0
subtract 5 from both sides
19x=-5
divide both sides by 19
x=-5/19
since side legnths can't be negative, we can cross this solution out
so x=5
subtitute
1+2x
1+2(5)
1+10=11
side a=11
11x+5
11(5)+5
55+5=60
side b=60
12x+1
12(5)+1
60+1=60
side c=61
add them all up
side a+b+c=11+60+61=132=total legnth
The easy thing to do is eliminate x by subtraction
x + 7y = 24
- x - 9y = -24
-------------------
16y = 48
now solve for y and then substitute the value into either original equation to find x
Adam made an error of 400 meters
Explanation:
Since, submarine traveling 200 meters below the surface of the ocean
and when the depth increases by 45 meters then submarine new location is
meters below from the surface of ocean.
But Adam says that new location is at -155 meters.
So, error is, 
meters
Learn more:
https://brainly.in/question/13000874
top middle, square, and right triangle. to find perimeter you simply add all of the side lengths :)
