Given :
To Find :
Solution :
We know that,
[tex]{ \qquad \: \pmb{ \dfrac{1}{2} \times (sum \: of \: the \: parallel \: sides) \times height} = \pmb{Area_{(trapezium)}}}[/tex]
Now, Substituting the given values in the formula :
[tex]\qquad { \dashrightarrow \: { \sf{ \dfrac{1}{2} \times (16 + x)\: \times 10 \: = {140}}}}[/tex]
[tex]\qquad { \dashrightarrow \: { \sf{ 5 \times (16 + x)\ \: = {140}}}}[/tex]
[tex]\qquad { \dashrightarrow \: { \sf{ 80 + 5x = {140}}}}[/tex]
[tex]\qquad { \dashrightarrow \: { \sf{ 5x = {140 - 80}}}}[/tex]
[tex]\qquad { \dashrightarrow \: { \sf{ 5x = {60}}}}[/tex]
[tex]\qquad { \dashrightarrow \: { \sf{ x = { \dfrac{60}{5} }}}}[/tex]
[tex]\qquad { \dashrightarrow \: { \pmb{ x = { 12 }}}}[/tex]
Therefore,