For what value of the constant $\displaystyle {c}$ is the function $\displaystyle {f}$ continuous on $\displaystyle {\left(-\infty,\infty\right)}$ where
$\displaystyle {f{{\left({y}\right)}}}={\left\lbrace\begin{array}{ccc} {y}^{{2}}-{c}&\text{if}&{y}\lt{7}\\{c}{y}+{7}&\text{if}&{y}\geq{7}\end{array}\right.}$


$\displaystyle {c}=$ Preview Question 6